This invention is generally in the field of ophthalmic therapies, and more particularly to the use of microneedles for local drug delivery to and/or diagnostic sensing in ocular tissues.
The delivery of drug to the eye is extremely difficult, particularly delivery of macromolecules and delivery to the back of the eye. Many inflammatory and proliferative diseases in the posterior region of the eye require long term pharmacological treatment. Examples of such diseases include macular degeneration and diabetic retinopathy. It is difficult to deliver effective doses of drug to the back of the eye using conventional delivery methods such as topical application, which has poor efficacy, and systemic administration, which often causes significant side effects. (Geroski & Edelhauser, Invest. Ophthalmol. Vis. Sci. 41:961-64 (2000)). For example, while eye drops are useful in treating conditions affecting the exterior surface of the eye or tissues at the front of the eye, the eye drops cannot penetrate to the back of the eye, as may be required for the treatment of various retinal diseases.
Direct injection into the eye, using conventional needles and syringes is often effective, but requires professional training and raises concerns about safety. (Maurice, J. Ocul Pharmacol. Ther. 17:393-401 (2001)). It also would be desirable to be able to minimize the number and/or frequency of eye injection treatments needed to effect delivery of a selected quantity of drug.
It therefore would be desirable to provide better, safer, more effective techniques for the direct delivery of therapeutic agents to eye tissues. It also would be desirable to provide devices useful in such techniques which can be relatively inexpensive to produce and use. It further would be desirable to provide methods for pinpoint delivery of drug to scleral or corneal tissues.